Organic electroluminescent diodes are devices (OLEDs), where organic molecules emit light when a driving voltage is applied to such organic electroluminescent devices. The OLEDs typically comprise a transparent substrate with an electroluminescent layer stack deposited on top of the substrate comprising an organic light emitting layer stack arranged between two electrode layers, typically a transparent anode made of Indium Tin Oxide (ITO) on top of the substrate and a reflective cathode made of aluminum on top of the organic layer stack. Since the organic molecules are sensitive to moisture and oxygen, the layer stack is encapsulated by a gastight cover lid sealed on top of the substrate. In order to operate the OLED, driving voltages in the order of a few volts, e.g. 2-15 V are applied. Due to the optical properties of the organic layers and the transparent substrate and resulting total reflection at the surfaces between organic layers and substrate as well as between substrate and air, only 20% of the light generated within the organic layer is coupled out of the organic electroluminescent device. The majority of the generated light is trapped within the glass substrate and the organic layers. It would be desirable to obtain an organic electroluminescent device, where the light out-coupling can be improved.